Depressive symptoms at subsyndromal levels and low energy are common in late stage HIV illness. Endocrine and metabolic abnormalities also occur frequently, of which testosterone deficiency is reportedly the most common. Since testosterone is both an androgenic (virilizing) and anabolic (weight regulating) hormone, there may be a connection between low testosterone, sexual dysfunction, low energy and metabolic disorder as well as depressed mood. We postulate that this symptom cluster represents a testosterone deficiency syndrome and propose to assess testosterone replacement therapy. As people with AIDS live longer, quality of life issues are increasingly recognized as salient. Anecdotal reports suggest that testosterone replacement therapy in later stage HIV illness not only restores libido and sexual function, but enhances mood, energy and appetite. By encouraging adherence to medical regimens (often arduous in late stage illness) these improvements may promote duration of life as well. We wish to assess the effects on low mood of testosterone replacement therapy, in men with progressive HIV illness, clinically deficient testosterone levels, and sexual dysfunction. Associated features include low energy and low appetite/weight loss. Treatment has two phases. The first consists of open treatment for 12 weeks with biweekly intramuscular injections of depot testosterone ester, with serum levels assessed one week after each injection. In Phase 2, responders at Week 12 are randomly assigned to double blind discontinuation by placebo or maintenance on active testosterone. Outcome measures include Week 12 response rate by self report and clinician judgement as well as relative relapse rates after the double blind discontinuation phase. Mood, sexual, energy and appetite changes as well as treatment emergent adverse reactions will be assessed at baseline and biweekly thereafter. Strength (hand grip) and nutritional status (body composition) as well as physical, endocrine measures and T cell subsets will be assessed at baseline, Week 12 and study endpoint both for safety considerations and to determine whether changes in these measures are associated with clinical outcome. The proposed study is meant to identify a practical and clinically useful treatment for community settings.